Symptom Cluster Heterogeneity and Gut Microbiota Mechanisms in Childhood Cancer Survivors

Inclusion Criteria for Children: * Aged 8-18 years; * Clinically and pathologically confirmed diagnosis of cancer (including leukemia, lymphoma, central nervous system tumors, or other common solid tumors); * Currently in the rehabilitation/maintenance phase or completed treatment ≥6 months prior to enrollment; * No cognitive impairment; able to understand, communicate, and complete questionnaires independently; * Written informed consent/assent obtained from participants and their legal guardians. Exclusion Criteria for Children: * Presence of severe treatment-related sequelae (e.g., significant organ dysfunction or neurological impairment) that may interfere with symptom assessment; * Poor compliance or inability to independently complete interviews/questionnaires; * Concurrent participation in other interventional clinical trials that may influence study outcomes; * Planned major surgery or initiation of new chemotherapy/radiotherapy during the study period. Inclusion Criteria for Caregivers: * Primary caregiver of an eligible CCS participant; * Aged ≥20 years; * Able to understand study content and complete questionnaires, with adequate literacy and communication ability; * Written informed consent provided prior to participation. Exclusion Criteria for Caregivers: * Experience of major adverse life events within the past 6 months (e.g., bereavement, divorce) that may affect psychological assessment * Presence of severe cognitive impairment; * Presence of severe aphasia, psychiatric disorders, or other conditions preventing independent completion of assessments.